In a known internal combustion engine, such as described, for instance, in Patent Document 1, listed below in paragraph [0003] an EGR path connects an exhaust path and an intake path, and an EGR catalyst and an EGR valve are disposed in the EGR path. The invention disclosed in this patent document changes a target air-fuel ratio from rich to lean if a threshold value is exceeded by the accumulated time during which the air-fuel ratio of exhaust gas flowing in the exhaust path is rich when EGR (exhaust gas recirculation) is provided with the EGR valve open. According to control exercised in the above situation, the EGR catalyst can be regenerated while EGR is provided.